Elongate, conduit-like chutes are often used to move granular material, grain seeds for example, from one location to another. Often, such chutes are fed from hoppers containing the granular material and the chutes may be fed by gravity, by pressurizing the hopper or by a combination of these. It frequently becomes necessary to effect closure of the chute during hopper refilling, when the chute and its associated system are being moved to a different location or for other reasons.
In addition, there may be a need to operate the closure apparatus even though the chute may be filled with material. Depending upon the configuration of the system, it may also be necessary to operate the closure apparatus from a remote location.
One approach to the construction of a chute closure apparatus is shown in U.S. Pat. No. 3,779,428. This mechanism uses a gate which moves about a pivot access located generally coincident with a wall of the chute. The gate is arranged to be manually positioned by a grasping handle and when moved in a direction to close the chute, must urge the material contained therein upward against the force of gravity or other motive force. During closure movement, the gate presents a very large surface area to the granular material. Therefore, the force required to move the gate to a closed position may well be high, perhaps so high that closing movement is impossible. In addition to the foregoing, the gate occupies valuable space within the interior of the chute when the gate is lodged in the open position. The maximum flow capacity of the chute is thereby impaired.
Various closure devices are also shown in U.S. Pat. Nos. 3,545,653; 2,648,867; 1,940,081; 414,725; 1,368,970; 1,767,904; 1,746,410; 162,734 and 9837.
Such structures have failed to address the need for a chute closure apparatus which provides excellent sealing closure of the chute, which is readily operable even when the chute is filled with granular material and which may be arranged to be positioned from a remote location. A chute closure apparatus which provides these benefits and which may be readily constructed and installed on a chute would be distinct advance in the art.